NEW: Mayor: "We hope the killers are caught before any more people are lost"

Kaufman County DA Mike McLelland and his wife, Cynthia, are found dead in their home

Two months ago, McLelland's deputy was shot to death outside the county courthouse

Investigators are not sure whether the deaths are linked

(CNN) -- Two months ago, a Texas district attorney vowed to put away the "scum" who had killed one of his top deputies.

Now, the district attorney and his wife are dead. And authorities aren't sure whether their killings are part of a broader scheme targeting criminal justice officials.

The bodies of Mike McLelland and his wife, Cynthia, were found Saturday in their home in Kaufman County, east of Dallas.

"I don't know of anyone who would want to cause him harm," Kaufman city Mayor William Fortner said. "As far as I could tell, he was doing a really good job as a district attorney."

Fortner said police are taking "extra precautions" to try to ensure no one else is targeted.

"We lost some important people, and we hope the killers are caught before any more people are lost," he said.

A law enforcement official told The Dallas Morning News that a door was apparently kicked in, and "there are shell casings everywhere."

Authorities have not identified a suspect. Nor are they sure whether the deaths are related to the killing of Kaufman County Assistant District Attorney Mark Hasse, who was killed on his way to work in January.

The county sheriff's office brought in the FBI and the Texas Rangers to help with the investigation.

McLelland was an Army veteran who later earned a master's in psychology and became a psychologist for the Texas Department of Mental Health and Mental Retardation, the district attorney's website said.

He later earned his law degree and practiced as a defense attorney and mental health judge before becoming the county's district attorney.

McLelland and his wife leave behind two daughters and three sons. One son is a Dallas police officer.

Another top prosecutor slain

The McLellands were killed almost exactly two months after Hasse was shot to death in broad daylight outside the county courthouse on January 31.

Hasse had feared for his life and carried a gun to work, said a Dallas attorney who described herself as his longtime friend.

Colleen A. Dunbar said she spoke with Hasse on January 24. She said the prosecutor told her he began carrying a gun in and out of the county courthouse daily.

"He told me he would use a different exit every day because he was fearful for his life," Dunbar told CNN.

She said that Hasse gave no specifics on why he felt threatened -- only that he did.

McLelland called Hasse "a stellar prosecutor" who knew that threats were part of the job.

He vowed after Hasse's slaying to put away the "scum" who killed his deputy.

"I hope that the people that did this are watching, because we're very confident that we're going to find you," McLelland told reporters.

"We're going to pull you out of whatever hole you're in, we're going to bring you back and let the people of Kaufman County prosecute you to the fullest extent of the law."